Interspecific hybrid dogwood tree designated ‘KF 111-1’

ABSTRACT

An advanced generation interspecific hybrid of  Cornus kousa  and  C. florida  that is distinguished by its exceptionally high vigor, attractive foliage, very floriferous display of white floral bracts, high level of winter hardiness, tolerance of drought and shade, and high resistance to the incitants of Powdery Mildew and Dogwood Anthracnose.

BACKGROUND OF THE INVENTION

This new cultivar is a product of a longstanding detailed program ofinterspecific hybridization and selection of dogwoods, in this instancea cross of an F₁ interspecific hybrid of Cornus kousa×C. florida‘Sweetwater’ backcrossed to an unrelated C. kousa. The progeny werecarefully retained and characteristics analyzed for their differencesand outstanding value as potential commercial varieties or cultivars.

The particular seedling hereof were selected from certain progeny grownin a cultivated area and, as a result, have in turn been asexuallyreproduced by grafting, usually by T-budding or chip-budding. It canalso be propagated by softwood stem cuttings. The reproduction andactual growth and selection of the new cultivar took place in thevicinity of New Brunswick, N.J. and has been found to be distinctive asto its winter-hardiness in that area, USDA Plant Hardiness Map Zone 6a.This new cultivar is stable and reproduces true to type in successivegenerations of asexual reproduction.

As will be understood from the detailed description of the inventionthat appears hereinafter, the new cultivar is in fact outstanding andreadily identified as such. With the foregoing in mind, the descriptionthat follows will be understood as clearly defining the new cultivar,the desirable characteristics of which are the result of such a programas has been heretofore suggested.

SUMMARY OF THE INVENTION

The variety was originated or discovered in a cultivated area on ahorticulture farm near New Brunswick, N.J. from a cross in June, 1989between an F₁ interspecific hybrid (seed parent) resulting from acontrolled cross of Cornus kousa×C. florida ‘Sweetwater’, and an unnamedC. kousa (pollen parent). The complete parentage of the claimed plantcan be summed as follows:(Cornus kousa×C. florida ‘Sweetwater’)×C. kousaNone of the antecedent parent plants are patented.

The seedling which became this new cultivar emerged in a seed flat onMar. 8, 1991 and, subsequently, was transplanted to progressively largerplant-growing containers as follows: one gallon, Mar. 21, 1991;two-gallon, May 22, 1991; 3-gallon, Jul. 25, 1991; 4.5 gallon, Jun. 16,1992; 7 gallon, Apr. 13, 1993; 15 gallon, Aug. 6, 1993. On Oct. 10,1994, the plant was field planted at a research site in Millstone, N.J.where it has been thoroughly tested to the present time. It has alsobeen propagated in Tennessee and Oregon. To the best of our knowledge,this new variety is the first reported advanced generation interspecifichybrid of these two species. Furthermore, its fruit has ornamental valueas contrasted with other hybrids of these species. The fall foliage ofthe plant is quite spectacular.

BRIEF DESCRIPTION OF THE DRAWINGS

This new variety of dogwood is illustrated by the accompanyingphotographic drawings, depicting the plant by the best possible colorrepresentation using color photography. All color references below aremeasured against The Royal Horticultural Society Colour Chart (R.H.S.).Copyright 1966 Colors of foliage, floral bracts, and other plant partsmay vary from year to year depending on horticultural practices, lightconditions, air temperature, soil fertility, etc.

FIG. 1 shows the original seedling tree of the present invention after17 years;

FIG. 2 shows leaf and floral display of original seedling at the peak offloral display;

FIG. 3 shows a single flower head in bloom;

FIG. 4 shows two fruits which illustrate the difference between a fruitcontaining no drupelets with a viable developing seed, and a fruitshowing the enlarged fleshy area around a drupelet containing a seed;and

FIG. 5 shows the foliage and fruit (most contain no viable seed) onseveral branches.

BOTANICAL DESCRIPTION OF THE INVENTION

-   Botanical designation: (Cornus kousa×C. florida ‘Sweetwater’)×C    kousa.-   Variety denomination: ‘KF 111-1’

PLANT

-   Form: Tree.-   Growth habit: Tree branched low to ground with upright branches    which spread outward after about 10-15 years.    -   -   Height.—7.62 meters at 19 years.        -   Width.—6.71 meters at 19 years.

The ornamental value of the fruit display of ‘KF 111-1’ is acharacteristic that distinguished it from all of the current F1interspecific hybrids (our Stellar® series of dogwood plants being thethe only F₁ interspecific hybrids of C. kousa×C. florida) since plantsof those hybrids are completely sterile and the fruit they produce areof no ornamental value.

-   Plant vigor: Plants of this new variety are very vigorous. The    original seedling was 2.29 meters in height and well branched at the    end of the first growing season. Budded liners propagated and grown    in Tennessee typically reach a height of 0.91 to 1.22 meters in one    year, with a few reaching a height of 1.52 meters. One-year liners    are stout and well branched. The plants are much more vigorous than    any cultivars of C. florida or C. kousa known to the inventors and    are more vigorous than plants of any of the seven cultivars of the    Stellar® series of hybrid dogwood (F₁ generation interspecific    hybrids of C. kousa×C. florida).-   Cold hardiness: Original seedling has suffered no winter injury    during the 16 years it has been observed in the field at Millstone,    N.J. in USDA Plant Hardiness Map Zone 6a (−5° F. to −10° F.).-   Resistance to insects and disease: No insect or disease problems    were observed during the 16 years the original seedling of the    cultivar ‘KF 111-1’ has been tested in the field.-   Trunk: Circumference of the crown of the original seedling at the    soil level was 0.95 meters after 19 growing seasons. Moderate to    heavy exfoliating bark on basal 1.52 m of trunk.-   Color: 197D Greyed-Green Group in areas between lenticels and 197A    to 197B Greyed-Green group in areas of numerous lenticels.    -   -   Underside of exfoliating bark.—165B Greyed-Orange Group.        -   Surface under exfoliated bark.—165D and 165A Greyed-Orange            Group.-   Lenticels: Approximately 16/cm² on basal 1.83 meters of trunk. Shape    somewhat oval with a length of 1.24 mm and a wish of 0.88 mm, raised    edge and depressed center, coloration RHS 201A grey group, based on    n=10 observations.-   Texture: Sandpaper rough.-   Branches:    -   -   Color.—197B Greyed-Green Group.        -   Texture.—Fairly smooth with many small bumps (lenticels).        -   Crotch angle.—Large, basal branches — 70°-85°; smaller            branches — 25°-40°.        -   Internode length.—13.2 cm (n=25); range 8.9-20.3 cm. Wherein            n is the number of observations.

The two major branches originating on the central trunk at a height of20 cm and 31 cm above soil level constitute the structure of theoriginal seedling. The two side branches are slightly obovate in shapeand measure 16 cm and 19 cm in diameter at 19 years. The shape of thesmall lateral branches of the basal 2.5 meters of the tree are markedlyobovate in shape, giving them a muscular appearance near the point ofattachment, the stems becoming increasing rounded in form as theylengthen.

FOLIAGE

-   Leaf arrangement: Opposite-   Leaf size: Lamina

Average Range in Average Range in Year n length (cm) length (cm) width(cm) width (cm) 2005 10 14.25 11.1-15.5 9.38 8.3-10.8 2009 10 12.811.6-16.2 7.20 5.9- 9.1 

-   -   -   Tip.—Apiculate.        -   Shape.—Ovate.        -   Base.—Attenuate.        -   Margin.—Mildly crenulate.

-   Texture: Lamina flat and quite smooth on abaxial surface in spite of    a moderate number of small white hairs. Adaxial surface has a    prominent midrib and four, sometimes five, pairs of moderately    prominent pairs of lateral veins. Small, short hairs cover the    entire surface, which is downy due to many longer white hairs along    the edges of the midrib and the lateral veins.

-   Other features: Prominent dense tufts of long, light brown almost    submicroscopic hairs at the axils of the lateral veins and the    midrib.

-   Quantity: Many, densely foliaged.

-   Mature foliage color:    -   -   Adaxial.—Closest to, but darker than 137A Green Group with a            narrow line (144B Yellow-Green Group) on the midrib from the            tip of the petiole to the base of the uppermost pair of            lateral veins.        -   Abaxial.—Closest to 138D Green Group with a narrow line            (145C Yellow-Green Group) on the midrib.

-   Autumn foliage color: Attractive. Some leaves remain green (141A    Green Group and 143A Green Group) but most of the leaves are about    50% green with mottled areas of 166A Greyed-Orange Group, 145A    Yellow-Green Group, 14 B Yellow-Orange Group, 15A Yellow-Orange    Group and 187A Greyed-Purple Group.    -   -   Petiole.—Length: average 11 mm (range 6-15) n=20. Width:            average 1.7 mm (range 1-2) n=20. Color: 145A Yellow-Green            Group. Other feature: dense mat of short hairs (200B Brown            Group) at inner base (point of attachment).

-   Disease resistance: Asexually propagated plants of his hybrid    variety have been tested in New Brunswick, N.J.; Millstone, N.J.;    Winchester, Tenn.; and Boring, Oreg. with no evidence of    susceptibility to the incitants of Powdery Mildew or Dogwood    Anthracnose.

-   Shade tolerance: Plants of this new hybrid have proven to grow well    under conditions of 60%-65% shade, in addition to thriving under    complete exposure to full sunlight.

INFLORESCENCE

-   Location where observations were made: Research field in Millstone,    N.J.-   Type of inflorescence: Flowerhead. Dense, rounded mound.-   Number of true flowers per flower head:

TABLE 1 Number of true flowers per flower head: Year n average range2003 125 51.6 40-63 2004 10 53.6 50-58 2005 20 48.9 40-55 2006 33 51.343-61 2008 27 50.6 42-62 2009 25 48.0 43-57The average number of true flowers per flower head of this new cultivaris quite uniform from year to year.

TABLE 2 Peduncle: size and color: Average Year n length (cm) width (mm)Color 2005 15 7.1 2.1 145A Yellow-Green Group 2006 23 9.5 2.0 ″ 2009 257.2 1.9 ″

FLORAL BRACTS

-   Number: Four, in two opposing pairs:

TABLE 3 Size of floral bracts: Length of lower Width of lower Involucralspread of bracts (cm) bracts (cm) lower bracts (cm) Year n AverageAverage n Average 2005 30 5.28 6.11 15 10.75 2006 48 5.88 5.95 24 11.95Length of upper Width of upper Involucral spread of bracts (cm) bracts(cm) upper bracts (cm) Year n Average Average n Average 2005 30 5.895.43 15 11.99 2006 48 6.30 5.09 24 12.80The size of the floral bracts will vary due to environment factors suchas temperature, sunlight, rainfall and fertilizer practices. However,the lower, floral bracts are always shorter and wider than the upperfloral bracts.

-   Color: At start of floral display (early to mid-May):    -   -   Adaxial surface.—Closest to 150D Yellow-Green Group and            slightly lighter toward the tip; fine line of 51A Red Group            along the margins and tips of the bracts.        -   Abaxial surface.—Closest to 150D Yellow-Green Group with            155D White Group toward tip and base; trace of 51A Red Group            at margins and tip. One week after the start of the floral            period:        -   Adaxial surface.—Closest to 4D Yellow-Group with trace of            52B Red Group along margins and tip.        -   Abaxial surface.—Closest to 155B White Group with trace of            52B Red Group along margins and tip.-   Shape: Broadly rounded-   Apex: Abruptly acute-   Base: Broadly acuminate-   Bract stalk length: 3-4 mm-   Bract stalk width: 5-6 mm-   Bract margins: Entire.-   Flower description: Very floriferous. Single flowers arranged in    compact, dense heads subtended by the large floral bracts. No    observed fragrance. Flowers not persistent.-   Flowering habit: Anthesis of the tiny, relatively inconspicuous true    flowers generally commences 4-6 days following the onset of the    ornamental display of the large floral bracts which generally occurs    in central New Jersey in early to mid-May and continues    approximately for 2.5 to 3 weeks or more depending on the prevailing    weather conditions. Floral development is asynchronous within the    inflorescence.

REPRODUCTIVE ORGANS

-   Stamens: Number per flower—4.    -   -   Filament size.—4-5 mm long and 0.25-0.30 mm wide.        -   Anther size.—Approximately 1.0 mm long and 0.56 mm wide.        -   Color.—Pre-anthesis: closest to 12A Yellow Group.            Post-anthesis: closest to 153D Yellow-Orange Group. Pollen            color — closest to 20A Yellow-Orange Group. Pistil: Number —            1.        -   Style length.—Approximately 1.5 mm long and 0.5 mm diameter.        -   Stigma height.—Approximately 0.25 mm.        -   Color of style.—145A Yellow-Green Group.        -   Color of stigma.—Closest to 153C Yellow-Green Group.

FRUIT

-   Flower head with mature fruit: Fruits are many two-celled, one    seeded drupelets (ovary inferior), fused at the base in areas    surrounding a drupelet containing a developing seed, and forming a    multiple fruit. A low percentage of the drupelets contain a    developing seed, whereas all of the known F₁ interspecific hybrids    of C. kousa×C. florida in commerce are extremely cross-sterile.    However, a multiple fruit of ‘KF 111-1’ does not develop into a    smooth, rounded, strawberry-like fruit similar to that of C. kousa    unless there are a number of drupelets that contain a developing    seed which stimulates basal fusion and enlargement of surrounding    drupelets. Thus, the external surface of the fruit is rough, albeit    rounded, due to the small protruding drupelets that do not contain a    developing seed. An aggregate fruit of C. kousa is plump and rounded    with a smooth surface even in the absence of any developing seed.    The multiple fruit of the ‘KF 111-1’ hybrid matures in mid-September    in the vicinity of central New Jersey.-   Size of fruit: Height in cms: 2.7 cm (n=43); width in cms: 3.1 cm    (n=43).-   Color: Large fused ovaries near a seed — 46A and 46B Red Group.    Smaller, protruding ovaries without a seed: 45A Red Group.-   Seed: Round and narrowly tapered to four sections at proximal end.-   Color: 161C-161D Greyed-Yellow Group.-   Size: Average length — 7.24 mm (n=15). Average width — 4.62 mm    (n=15).-   Texture: Rough.

1. A new and distinct cultivar of dogwood tree, substantially as hereinshown and described, comprising an advanced generation interspecifichybrid of Cornus kousa×C. florida ‘Sweetwater’ with an unrelated plantof C. kousa.